Atheists attack Christianity, and not other religions, because they already know God exists and who He is.
Well, we for one (granted, not everyone here is an atheist, but I am one and have posted such content), and we’ve mocked Jews, Muslims, weird New Age cults, weird Nezi Pagan cults, at least one Hellenic neopagan…
Have you considered that most open atheiists/most atheists you are aware of may come from are from your own society, and that one’s local domninant religion (Christianity, in this case) is both the one they are likely most familiar and thus qualified to comment on the one that is most likely to be an active concern? And yes, say, Indian atheists very much do attack Hinduism.
And what about ferociously Islamophovic atheists like Sam Harris?
Their irrational anger and hatred is evidence that they know God exists.
Why would anyone be angry at a Being who doesn't exist?
Plenty of people are offended at character that they perceive to be badly written. Does this mean Edward Cullen, Wesley Crusher or whoever is the latest target of the Nerd Right’s outrage machine are real, too?
Anyways, far more often, we are angry at the - very real - people who worship such an abhorrent being, hold it up mas the ultimate paragon of all that is good and are willing and eager to commit atrocities in its name.
(And no, such believers are not unique to your own god. After all, would the Aztecs have performed all those elaborate mass human sacrifices for a lie?)
Even though there is no evidence for abiogenesis or macroevolution.
Common Descent – let alone evolution above the levels you typically assign your “kinds” to - is beyond well documented. And nowadays, we are far from clueless on abiogenesis, either.